[ietf-dkim] Responsibility concerns with Designated Signing Domains
fenton at cisco.com
Fri Aug 25 14:48:57 PDT 2006
While we aren't defining reputation or accreditation services in this
working group, it has been widely suggested that such services would use
the d= domain on the signature as the "lookup key" for retrieving
reputation or accreditation information.
There is a fundamental difference, then, between key delegation and
delegation via SSP. In the former (key delegation) case, the party
applying the signature (delegatee) is merely acting as an agent of the
delegator to do the mechanics of signature application. It is still
the delegator's signature, and the "buck stops" with the delegator in
terms of who has taken responsibility for the message. In the latter
(SSP delegation) case, it is the delegatee's domain that takes
responsibility for the message. Some have suggested the delegatee might
want to use subdomains in order to allow reputations to avoid
aggregating reputations from different delegators (or classes of
Some implications of this change in responsibility:
1. Responsible domains using SSP delegation will not be able to change
signing providers (delegatees) without forfeiting any positive
reputation they have accumulated. It should really be the delegator's
positive reputation, because they are the ones acting responsibly in
their mailing practices and/or the use of outside mailing providers. It
should not be necessary to start over if you change ISPs or outbound
2. Delegators are more likely to be diligent in the choice of delegatees
when it is their own reputation at stake. When it is the delegatee's
reputation at stake, they can always employ an unreliable party, or in
the extreme a spammer, and when abuse is reported simply say "oh, sorry"
but not endure any impact on their reputation at all.
3. We are already aware of the potential for the use of throw-away
domain names by bad actors who otherwise might accrue a bad reputation.
This opens a new possibility: it isn't necessary to get a new domain,
just delegate signing to a new entity and "all is forgiven".
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